Mining pools in the bitcoin works because the members of a pool can prove that they are working hard by sending in their "near-valid" hashes to the...

Mining pools in the bitcoin works because the members of a pool can prove that

they are working hard by sending in their "near-valid" hashes to the pool manager. What

measure can a designer of a blockchain take in designing their proof-of-work puzzle or in

the way blocks are formed so that mining pool formation will be highly discouraged?